This invention relates in general to pliers for forming and removing bumps on dental repositioning appliances.
Orthodontic treatments involve repositioning misaligned teeth and improving bite configurations for improved cosmetic appearance and dental function. Repositioning teeth is accomplished by applying controlled forces to the teeth over an extended period of time. This is conventionally accomplished by wearing what are commonly referred to as xe2x80x9cbraces.xe2x80x9d Braces comprise a variety of appliances such as brackets, bands, archwires, ligatures, and O-rings. After they are bonded to the teeth, periodic meetings with the orthodontist are required to adjust the braces. This involves installing different archwires having different force-inducing properties or by replacing or tightening existing ligatures. Between meetings, the patient may be required to wear supplementary appliances, such as elastic bands or headgear, to supply additional or extraoral forces.
Although conventional braces are effective, they are often a tedious and time consuming process requiring many visits to the orthodontist""s office. Moreover, from a patient""s perspective, they are unsightly and uncomfortable. Consequently, alternative orthodontic treatments have developed. A particularly promising approach relies on the use of elastic positioning appliances for realigning teeth. Such appliances comprise a thin shell of elastic material that generally conforms to a patient""s teeth but is slightly out of alignment with the initial tooth configuration. Placement of the elastic positioner over the teeth applies controlled forces in specific locations to gradually move the teeth into the new configuration. Repetition of this process with successive appliances with new configurations eventually move the teeth through a series of intermediate configurations to a final desired configuration. A full description of an exemplary elastic polymeric positioning appliance is described in U.S. Pat. No. 5,975,893, and in published PCT application WO 98/58596 which designates the United States and which is assigned to the assignee of the present invention. Both documents are incorporated by reference for all purposes.
In addition to their ease of use, polymeric positioning appliances are generally transparent, providing an improved cosmetic appearance, and impart substantial force on the teeth, due to stiffness of the appliance. The stiffness of an elastic positioning appliance is a result of the modulus of the polymer materials from which it is made. The higher the modulus of the materials, the higher the stiffness of the appliance. When a patient positions such an appliance over a prescribed group of teeth, one or more of the teeth will provide a base or anchor region for holding the positioning appliance in place while the stiffness of the polymeric material will impart a resilient repositioning force against one or a portion of the remaining teeth. However, the stiffer the appliance, the more difficult it is to slip the misaligned appliance over the teeth and fully engage the appropriate surfaces; the appliance often has the tendency to disengage or xe2x80x9cpop offxe2x80x9d. Likewise, once it is firmly seated, it is more difficult to remove. Further, a stiff appliance is less forgiving in cases of lowered patient compliance. If a patient were to remove the appliance for an unprescribed period of treatment time, the patient""s teeth may move slightly out of the planned tooth arrangement. When attempting to reapply the appliance, it may be too rigid to accommodate these slight differences and a new appliance may need to be created. Similarly, the tooth positions defined by the cavities in each successive appliance must not differ beyond a limiting dimension from those defined by the prior appliance or, again, it may be too rigid to accommodate the differences. Consequently, only small increments in tooth repositioning may be made with each appliance.
During application of the appliance, it is useful to form bumps in a polymeric appliance to facilitate minor orthodontic movements. The bumps apply corrective pressure to a patient""s teeth allowing the doctor to optimize the adaptation of the appliance to the teeth. One method of forming these bumps is by using a heated rod that works like a soldering iron to form a cylindrical bump in the appliance. The soldering iron must be heated electrically and works effectively only on specific polymeric materials, rather than on all polymeric materials.
U.S. Pat. No. 6,293,790 to Hilliard entitled xe2x80x9cHeated orthodontic pliersxe2x80x9d relates to an assortment of orthodontic pliers that are capable of forming different shaped ramps, imprinted logos, logo pockets, fluoride and bleach pockets, bite plates, rectangular shapes for retention of blocks on any polymeric appliance and pinching down on loose fasteners when heated to a sufficient temperature. This will allow orthodontists to make the minor modifications that are often necessary in a cost effective manner. The Hilliard patent specifically noted that xe2x80x9c[no] patent discloses the necessity to heat the dental pliers for forming bumps or pinching loosely held fasteners in the polymeric appliance.xe2x80x9d
A system to form and erase bumps on a dental appliance without heating is disclosed. In one aspect, dental pliers to create a bump in a dental appliance without requiring heating include a first elongated member having a first jaw portion at one end and a handle portion at the other end, the jaw portion having a projection mounted at a distal end of the first jaw portion; and a second elongated member joined to the first elongated member, the second elongated member having a second jaw portion at one end and a second handle portion at the other end, the second jaw portion adapted to receive the projection to create the bump in the dental appliance without heating.
In another aspect, eraser pliers for erasing the bump include a first elongated member having a first jaw portion at one end and a handle portion at the other end, the jaw portion having flat surface mounted at a distal end of the first jaw portion; and a second elongated member joined to the first elongated member, the second elongated member having a second jaw portion at one end and a second handle portion at the other end, the second jaw portion having a second flat surface mounted at a distal end of the second jaw portion, the first and second flat surfaces adapted to engage and flatten the bump.
Implementations of the above aspect may include one or more of the following. The second handle is pivotally joined to the first handle. The appliances can be made from a polymeric material such as a hard block polyurethane polymer such as IsoplastTm manufacture by Dow Chemical, TecoplastTm manufacture by Thermadics Polymer Products, polyester polycarbonate blends and polycarbonate such as XylexTm and LexanTm respectively manufacture by GE Corporation, and polyester homopolymer such as EastarTm manufacture by Eastman Chemical. The material may be from the classes of polymers given above as examples but not limited to those alone. The material may be homopolymer, heteropolymer, polymer blends, coextruded polymer with each layer being a different material or the same material and may be in different thicknesses. The material may also be a thermalset or any suitable material capable of elongation in accordance with the design and dimensions dictated by the pliers"" tips without causing puncture.
In another aspect, dental pliers for erasing a bump formed on a dental appliance, includes a first handle having a first tip with a flat surface positioned thereon; and a second handle pivotally joined to the first handle, the second handle having a tip with a flat surface adapted to engage the first flat surface to flatten a projection at room temperature.
Advantages of the invention may include one or more of the following. The pliers can be used for either forming or removing bumps or pressure points on orthodontic polymeric appliances. Bumps may be formed on the appliance surface resulting in orthodontic pressure that allows for the minor repositioning of teeth. The ability to fabricate bumps provides the doctor with increased flexibility and options during treatment. The bumps may be used to accomplish minor anterior rotations, minor anterior in-out tooth movement, tightening light interproximal contacts and enhancing appliance retention in undercut regions. The pliers are designed to allow for the fabrication of bumps without heating any part of the pliers jaw. This is achieved by designing the jaw tips to allow the polymeric to be stretched at ambient conditions.